ReleaseEngineering/PuppetAgain/HowTo/Build RPMs

How to Build RPMs

Install Mach

Start with a minimal install of CentOS 6.2.

$ yum install wget createrepo gcc make
$ wget http://thomas.apestaart.org/download/mach/mach-1.0.2.tar.gz
$ tar xzf ./mach-1.0.2.tar.gz
$ cd mach-1.0.2
$ ./configure --disable-selinux
$ make
$ make install
$ chmod u+s /usr/local/sbin/mach-helper
$ groupadd mach
$ useradd -g mach -m mach
$ passwd mach

Due to a permissions bug I hit with mach (during a file copy), we'll continue as root.

Create /root/.machrc:

config['centos-6-x86_64-os']['macros']['dist'] = '.el6'
config['centos-6-i386-os']['macros']['dist'] = '.el6'

Prepare the Package

For this example, I want to build a new mozilla-python27 package based on 2.7.3 instead of 2.7.2. I'm going to fetch the original .src.rpm and extract it into a subdirectory:

$ wget http://repos/repos/yum/releng/public/CentOS/6/x86_64/mozilla-python27-mercurial-2.1.1-4.el6.src.rpm
$ mkdir mozilla-python27 && cd mozilla-python27
$ rpm2cpio ../mozilla-python27-mercurial-2.1.1-4.el6.src.rpm | cpio -ivd

Then edit these .spec file lines to update the Python version and package release number:

%define pyrel 3
Release:        0%{?dist}

Build the Package

Now we want to rebuild the package using our updated .spec file.

$ rm -rf /usr/local/var/tmp/mach/*
$ mach='mach --debug -r centos-6-x86_64-os'
$ $mach clean
$ $mach build mozilla-python27/python27.spec

Note: adjust the target to 'centos-6-i386-os' to generate a 32-bit package.

In this case, though, I wanted to use mock (not mach) to build the final package since my mach build machine does not have access to the Mozilla yum repos. We can use the .src.rpm generated above and feed that to mock.

Note that this is a simple example. mach has an advantage over mock in that it figures out dependencies when building multiple packages and automatically pulls in source files (normally a manual operation). This can save a lot of time and hassle.

Configure Mock

• Install mock
• Copy the mock-config folder to your home directory (this example uses /home/cltbld/mock-config).

Build Using Mock

• Fetch the .src.rpm you built earlier.
• Execute these steps to build:

$ mock='mock --configdir=/home/cltbld/mock-config -r epel-6-x86_64 -v'
$ $mock --rebuild mozilla-python27-2.7.3-0.el6.src.rpm

• The script will tell you where the results are available.
• Use 'epel-6-i386' to build a 32-bit package.

Build an .src.rpm Using Mock

Find a suitable machine with 'mock' installed. It's best to do this on a target machine, since its /etc/mock/default.cfg will already be set up correctly.

Download the srpm from puppetagain.pub.build.mozilla.org/data/repos/yum/releng/public and unpack it:

mkdir foopkg && cd foopkg
rpm2cpio $srpm | cpio -ivd

You should see a .spec file appear. Check that it is identical to the one in http://hg.mozilla.org/build/puppet under modules/packages/manifests/mozilla e.g., with an md5 hash. If not, figure out what the differences are, and which corresponds to the running version of the package.

Edit the spec file to your heart's content. To build an RPM, you'll need to stop off at an SRPM:

mock --buildsrpm --spec /path/to/spec --sources $PWD

The script output will tell you where the SRPM is. Copy it somewhere else, or mock will delete it. Then build the SRPM into an RPM:

mock --rebuild /path/to/srpm

Other Dependencies

If your package depends on other mozilla-specific packages, I'm not sure what the best way to build is. The less-than-awesome technique I used was to hack /etc/mock/epel-6-x86_64.cfg to include pointers to the public mirrors of the puppetagain repos.

Testing

For testing purposes, it's best to install the RPM locally, rather than dropping it into the puppetagain data directory and risking affecting production. You can do that too, if you're confident it won't affect anything.

Review

For review, include the modified .spec in your r? for changes to the puppet repository.

Remember, if the package can't be 100% re-created from data in the PuppetAgain Mercurial repository, you're doing it wrong!

Landing

See ReleaseEngineering/PuppetAgain/Packages for details on landing the change.